Tommy Robinson, real name Stephen Yaxley-Lennon, gave evidence about his finances after losing a libel case.
The 39-year-old was ordered to pay damages to Syrian teenager Jamal Hijazi after defaming him online.
Robinson told the court he owed hundreds of thousands of pounds when he declared himself bankrupt last year.
Appearing at the Royal Courts of Justice in London at a hearing to discuss money he owes, he said at one point he was spending about £100,000 on gambling in casinos and online.
He described how he wasted money on "drink, alcohol, partying" while receiving thousands of pounds in donations from supporters.
Robinson said in 2020 he received about £1,000 a month from supporters and at times that figure was between £3,000 to £4,000.
He was asked about claims in his bankruptcy form that he owed a debt of £323,000 to Bedfordshire businessman Christopher Johnson.
He told the court the "successful businessman" had "cash, a lot of cash" but the pair fell out and the relationship "went pretty sour" and it "wasn't realistic" to pay him back.
Talking about the build-up to his bankruptcy in March 2021, he said he was a "total mess" and had "suffered a total mental breakdown for two or three years".
He added: "I owe loads of money. Can't get out of it."
He said that for some of the time he was "sofa surfing" between about seven different addresses.
Robinson said he was not currently living in the UK and only returned when he was working.
Asked about a claim in his 2009 book Enemy of the State that he owned seven properties, but six of them were in his wife's name, he said: "I like to give off that I am a successful man when I am not."
Jamal Hijazi was assaulted at Almondbury Community School in Huddersfield in October 2018.
After the incident went viral, Robinson made false claims about Mr Hijazi, leading to the libel case.
The current hearing was called to discuss the £43,293 Robinson owed from a court order made in December 2020.
Since then he has been ordered to pay £100,000 in damages to Mr Hijazi and further significant legal costs.